The Hale Telescope was the brainchild of astronomer George Ellery Hale.
He secured funding from the Rockefeller Foundation, and construction began in 1935, but the first official photos weren’t taken by the telescope until January 1949. Under direction of Edwin Hubble, the telescope designed for photographic work captured Hubble’s Variable Nebula (NGC 2261) in the constellation Monoceros from the prime focus observing cage.
The Hale Telescope’s first offical photos captured Hubble’s Variable Nebula. Source: Palomar/Caltech
Research didn’t begin at the Hale Telescope until November 1949, 21 years into the project, but the 200-inch telescope is still in use, aiding in astronomical research including solar system studies, the search for extrasolar planets, stellar population and evolution analysis, and the characterization of remote galaxies. The Hale is known for its use of many pioneering technologies, such as vapor deposited aluminum and low thermal expansion glass.
Located at Caltech’s Palomar Observatory, the telescope was the largest aperture optical telescope until the BTA-6 was built in 1976, and second largest until the Keck 1 was completed in 1993. It is a reflector, a telescope whose primary optical element is a curved mirror, so there are no lenses in the telescope itself.
The Hale’s primary mirror is a 200-inch in diameter Pyrex disk that weighs 14.5 tons and is concave and covered with a thin layer of aluminum. The primary mirror, with an area of about 31,000 square inches, acts as a giant pupil that collects light from the universe.
The Hale’s 200-inch mirror is recoated approximately every two years. Source: Palomar/Caltech
The telescope has been used to correct the distance estimate of the Andromeda Galaxy, which effectively doubled the size of the universe, gain a new understanding of galaxy formation and stellar evolution, and discover quasars located several billion light-years away, which are among the most distant astronomical bodies ever observed.